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CN-122010566-A - Preparation process and application of isostatic special graphite product prepared from artificial graphite powder

CN122010566ACN 122010566 ACN122010566 ACN 122010566ACN-122010566-A

Abstract

The invention belongs to the technical field of special graphite preparation, and particularly relates to a preparation process and application of an isostatic pressing special graphite product prepared from artificial graphite powder, which solve the technical problems of complex and lengthy process, inherent defects of product performance and poor coupling between a raw material system and the process, and comprise the following two stages in sequence, namely, a special artificial graphite powder prefabrication stage, namely, taking calcined petroleum coke and/or calcined asphalt coke as raw materials, and sequentially carrying out selective pre-graphitization treatment, mechanical shaping, final-state graphitization, synchronous purification treatment and particle size classification to obtain artificial graphite powder serving as special aggregate; and (II) a product forming stage, namely combining the artificial graphite powder with a binder system containing nano carbon materials through a liquid phase compounding process, drying to obtain composite pressed powder, performing cold isostatic pressing on the composite pressed powder, and roasting the obtained green body for one time in a protective atmosphere to obtain the isostatic pressing special graphite product.

Inventors

  • ZHANG QINGBIN
  • SUN HAO
  • JIN BAOQING
  • HAO ZHIBO

Assignees

  • 辽宁国瑞新材料有限公司

Dates

Publication Date
20260512
Application Date
20260225

Claims (10)

  1. 1. The preparation method of the isostatic pressing special graphite product is characterized by comprising the following two stages in sequence: The preparation stage of the special artificial graphite powder comprises the steps of taking calcined petroleum coke and/or calcined asphalt coke as raw materials, and sequentially carrying out selective pre-graphitization treatment, mechanical shaping, final-state graphitization, synchronous purification treatment and particle size classification to obtain the artificial graphite powder serving as special aggregate; And (II) a product forming stage, namely combining the artificial graphite powder with a binder system containing nano carbon materials through a liquid phase compounding process, drying to obtain composite pressed powder, performing cold isostatic pressing on the composite pressed powder, and roasting the obtained green body for one time in a protective atmosphere to obtain the isostatic pressing special graphite product.
  2. 2. The method according to claim 1, wherein the special artificial graphite powder prefabrication stage comprises: a) The temperature of the selective pre-graphitization treatment is 1850 ℃ to 2150 ℃; b) The sphericity of the mechanically shaped powder particles is not lower than 0.90; c) In the final state graphitization and synchronous purification treatment, when the temperature reaches the initial temperature determined based on the sphericity of the powder, the halogen-containing purification medium starts to be introduced, and the introduction parameter of the purification medium is dynamically adjusted along with the temperature rise.
  3. 3. The method according to claim 2, wherein the initial temperature is set so that the value is not lower than a calculated value obtained by linearly combining a reference temperature value and the sphericity value of the powder in a predetermined ratio.
  4. 4. A method of preparing according to claim 2 or 3, wherein the dynamic adjustment is in any of the following ways: (i) Increasing the volume concentration of halogen gas in the purification medium stepwise with the increase of temperature; (ii) The purification medium is pulsed and the proportion of the duration of the aeration in the pulse period to the whole pulse period increases with increasing temperature.
  5. 5. A special artificial graphite powder for the preparation method of claim 1 is characterized by being prepared by a method comprising the steps of carrying out selective pre-graphitization treatment on calcined petroleum coke and/or calcined asphalt coke at 1850-2150 ℃ to obtain a pre-graphitization intermediate, carrying out mechanical shaping on the pre-graphitization intermediate to obtain shaped powder with sphericity not lower than 0.90, heating the shaped powder to 2800 ℃ or higher in an atmosphere containing halogen gas to carry out final graphitization and synchronous purification treatment, and grading the treated material to obtain the special artificial graphite powder, wherein the tap density of the special artificial graphite powder is not lower than 1.10g/cm <3 >, and the ash content is not higher than 50ppm.
  6. 6. The nano composite graphite pressed powder is characterized by comprising the special artificial graphite powder, a binder and a nano carbon material reinforcing agent dispersed in the binder, wherein the content of the nano carbon material reinforcing agent is 0.5% -3.0% of the mass of the special artificial graphite powder.
  7. 7. An isostatic special graphite product, which is characterized in that the product is prepared from raw materials containing the nano composite graphite pressed powder of claim 6 through cold isostatic pressing and one-time roasting processes, and simultaneously meets the following performance indexes: (1) The volume density is not lower than 1.88g/cm3; (2) The apparent porosity is not higher than 4%; (3) The flexural strength is not lower than 75MPa; (4) Isotropy the ratio of flexural strength measured in any two perpendicular directions is between 0.95 and 1.05.
  8. 8. The isostatic specialty graphite article according to claim 7, further meeting the following performance criteria: (5) Ash content is not higher than 40ppm; (6) The difference between the coefficients of thermal expansion in any two perpendicular directions is not more than 0.4X10 -6 /K in the range of room temperature to 600 ℃.
  9. 9. A roasting protection device for an isostatic pressing special graphite product is characterized by comprising a sealed crucible main body, a supporting frame arranged in the crucible main body and used for bearing a graphite green body, and a carbonaceous protection medium filled in the crucible main body and coating the graphite green body, wherein the carbonaceous protection medium comprises a mixture of two or more carbonaceous materials with different particle sizes.
  10. 10. Use of an isostatic specialty graphite article as claimed in claim 7 or 8 in a thermal field system of a high temperature crystal growth apparatus.

Description

Preparation process and application of isostatic special graphite product prepared from artificial graphite powder Technical Field The invention belongs to the technical field of special graphite preparation, and particularly relates to a preparation process and application of an isostatic pressing special graphite product prepared from artificial graphite powder. Background The isostatic pressure special graphite is an indispensable key material in the tip fields of semiconductors, new energy sources, nuclear energy, aerospace and the like because of high strength, high density, high purity and good isotropy. The traditional mainstream preparation process can be summarized as 'Jiao Mofen after calcination-kneading with asphalt-forming-roasting-dipping and roasting-graphitization'. The process has the main following bottlenecks: The process is complex and lengthy, the cycle of repeated dipping and re-baking significantly lengthens the production period, usually more than 3 months, and greatly increases the energy consumption and cost. The product performance has inherent defects that the ideal uniform dispersion of the binder and the aggregate is difficult to realize by the traditional dry-method hot kneading, and the product is easy to cause uneven microstructure, obvious anisotropism and large fluctuation of mechanical properties. Although the impregnation process can increase the density, it may introduce new non-uniformities and affect the dimensional stability at high temperatures due to the difference in thermal expansion coefficients of the impregnating agent and the matrix. The raw material system and the process have poor coupling, and the prior art focuses on the improvement of a single link. For example, there is a patent to optimize sphericity and purity of artificial graphite powder, but there is no solution to the difficulty of how to efficiently prepare a high isotropy bulk material based thereon. Disclosure of Invention The invention aims to provide a preparation process and application of an isostatic pressing special graphite product prepared from artificial graphite powder, so as to solve the technical problems. In order to achieve the above purpose, the specific technical scheme of the invention for preparing the isostatic pressing special graphite product from the artificial graphite powder is as follows: the preparation method of the isostatic pressing special graphite product comprises the following two stages in sequence: The preparation stage of the special artificial graphite powder comprises the steps of taking calcined petroleum coke and/or calcined asphalt coke as raw materials, and sequentially carrying out selective pre-graphitization treatment, mechanical shaping, final-state graphitization, synchronous purification treatment and particle size classification to obtain the artificial graphite powder serving as special aggregate; And (II) a product forming stage, namely combining the artificial graphite powder with a binder system containing nano carbon materials through a liquid phase compounding process, drying to obtain composite pressed powder, performing cold isostatic pressing on the composite pressed powder, and roasting the obtained green body for one time in a protective atmosphere to obtain the isostatic pressing special graphite product. Further, the special artificial graphite powder prefabrication stage comprises the following steps: a) The temperature of the selective pre-graphitization treatment is 1850 ℃ to 2150 ℃; b) The sphericity of the mechanically shaped powder particles is not lower than 0.90; c) In the final state graphitization and synchronous purification treatment, when the temperature reaches the initial temperature determined based on the sphericity of the powder, the halogen-containing purification medium starts to be introduced, and the introduction parameter of the purification medium is dynamically adjusted along with the temperature rise. Further, the initial temperature is set so that the value is not lower than a calculated value obtained by linearly combining a reference temperature value and the powder sphericity value in a predetermined ratio. Further, the dynamic adjustment is any one of the following ways: (i) Increasing the volume concentration of halogen gas in the purification medium stepwise with the increase of temperature; (ii) The purification medium is pulsed and the proportion of the duration of the aeration in the pulse period to the whole pulse period increases with increasing temperature. Further, in the product forming stage, the liquid phase compounding process comprises the steps of dissolving a binder in an organic solvent to form a glue solution, dispersing a nano carbon material in the glue solution to form a reinforced binder phase, adding and dispersing the artificial graphite powder in the reinforced binder phase under the stirring condition to form uniform slurry, and then removing the organic solvent. The binder com